The public-key and signature can now be POSTed at time of registration
These are validated by server before posting to blockchain, and can be
retrieved by users for validation on their local machines as well

Added appropriate HTTP codes as well

Modified contract to store and retrieve these values and various scripts
(server, batch reading/writing) to handle these new values

Change-Id: Iddcaa00ab0d7068cea6d578489eacb89e8354b7c